In a vehicle such as an automobile, a large number of electrical components are disposed in respective portions of a vehicle body. To operate and control such electrical components, a large number of electronic units are used.
Such electronic units include one which simultaneously includes a heat generating electronic component that generates heat through energization and a heat-susceptible electronic component (See Patent Literature 1, for example). In the electronic unit having such a configuration, it is required to protect the heat-susceptible electronic component from heat generated from the heat generating electronic component.
Accordingly, in the electronic unit disclosed in Patent Literature 1, a heat generating electronic component and a heat-susceptible electronic component are separately disposed in a casing by interposing a sealed space for thermal insulation between the components, for example. In addition, for the purpose of preventing moisture, each of the heat generating electronic component and the heat-susceptible electronic component is individually sealed with a thermosetting potting material having a heat conductivity higher than that of air.